query bug

Danielle et jean Thierry-Mieg mieg at kaa.crbm.cnrs-mop.fr
Sat Sep 21 06:11:31 EST 1996

The proposed BNF stress that:

1) Find all sequences that are on more than one chromosome map.  

WHERE COUNT(m FROM .Map m WHERE m = "Chr*") > 1

This search can not be done just now.
*********** true, a bug in the code, i try to fix it !

the correct present syntax is
FIND Sequence ; COUNT { FOLLOW Map chr* } > 1

note the {} casting the inside FOLLOW Map chr* to an embedded query

this query does NOT work in distributed 4.3
i have not tested deeper recursions with several embeded {{ }}
but the present syntax allows that in principle

finally, there is a parsing problem, semicolumns embeded inside the
{} arere allowed by the syntax but do break the parser

what i am aiming at is that one should distinguish 2 concepts
a) the bnf syntax
b) bugs in the implementations

that is, on this particular case, the new query is not better
but an implementation bug was noticed

As long as the expected result of the query is just a set of
objects, it is not clear that the proposed system has real
superiority, i think it is less concise and no more expressive

however, there is a big advantage when we come to tables,
I was never able to write down the BNF for the table maker, 
because i always thought it was too clumsy and I welcome
the notion of a unified query/table definition

my comments on the document by rd and weisman is:
  some little details of style
  an interogation about casting
i think explict casting should be allowed, so checking
of the query against the model would give much better
messages while compiling the query

finally i would prefer the syntax

 p = Paper
 a = p->author

to the syntax
 Paper p
 p.author a

and also would prefer class casting, possibly to subclasses

 p = Paper
 a = (Prolific_author) p->a


 i got an empty result with the query
 FIND Sequence ; COUNT {FOLLOW Map chr*} > 1
but i think this is normal, but i did verify that the query
  FIND Sequence zk* ; COUNT {FOLLOW Subsequence *6} > 0
which has the same grammar, does yield the expected 44 answers in 
the nematode data distrib


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